European Patent Application EP0537849A1 discloses automatic pulsating deliver of an irrigation liquid by using pressure-sensitive secondary valves which open or close to enable irrigation liquid to emerge.
U.S. Pat. No. 3,917,74 discloses emitters of different flow potential for supplying the same given amount of water at various line pressures. Specific line pressure at each hole in the feeder tube is measured and an emitter adapted to deliver the desired amount of water is selected and installed at the location.
U.S. Pat. No. 6,786,425 discloses an actively operable check valve to selectively exert first and second pressures on the check valve. The valve permits the passage of spray fluid at one of the first and second pressures.
U.S. Pat. No. 8,348,182 discloses an irrigation pipe with integrated emitters having different discharge-pressure thresholds.
U.S. Patent Publication 2005/0279856 discloses a pipe and emitter assembly having a sealing adapter, an emitter tube, and a pressure compensating flow emitter. A controller adjusts irrigation parameters based on data.
U.S. Patent Publication 2014/0374502 discloses a flow regulating drip emitter with labyrinth passageways with different resistance to water flow, wherein movement of a cover selects a passageway.
PCT Publication WO 2010/061375 A1 discloses a drip irrigating system with a pulsating device that converts a low continuous liquid flow rate to a high intermittent and pulsating flow rate, connected to a manifold of pressure-compensated drippers.